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TOPIC: S30 V

Re: S30 V 1 year 9 months ago #8368

  • Geocyclist
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Phil,

Please expand on why 20 degrees would be sharper. Is this because you think S30V can't take a very shallow angle? I have heard that if you take too shallow for the steel the edge will not hold up, i.e bascially exceeded the strength of the steel.

Are there other reasons that an acuter angle is sharper?
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Re: S30 V 1 year 9 months ago #8370

  • PhilipPasteur
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I knew that was coming
The terms edge angle and included angle can be important when talking about grinding. The edge angle is measured between the surface of an edge and a line running from the point of the cutting edge to the back edge. The included angle is the sum of the edge angles. All other things being equal, the smaller the included angle the sharper the blade and the easier it is to damage the edge.

en.wikipedia.org/wiki/Grind

There has been many discussions about this that I have read in many places. I think the consensus (a hard thing to find on the Internet) is that the smaller the included angle the finer an edge can be put on it and the better it cuts. The thinner bevel also reduces cutting force requirements because it offers less friction.

Check out some of the Japnese knife discussions where they take the super hard steels to at or under 10 degrees on a single bevel... for ease of cutting... sharpness!

As with anything there are trade offs. If the steel will not support the angle such that the edge rolls or chips out, then you are wasting your time. Softer but tough steels often have a larger included angle so that they will not deform. Harder high carbide steels can be brittle and chip out. The whole idea of super steels is to combine materials to try to get the best of all worlds. They look for toughness, abrasion resistence, hardenability edge retention and fine grain structure... etc. S30V is claimed to have good ratings in all of these, especially CPM touts its increase in toughness. From what I have seen it is typically hardened to 60 to 61 Rc

What does that mean, well you should easily be able to run 20 degrees per side with no problems. On that Military, I have run 17 degrees per side for over a year and had no problems with chipping or edge rolling. Now I admit, I have not chopped hardwood with it nor done any batonning... nor cut anything harder than plastic banding material and tie wraps, but it has survived lots of medium type use like a champ.

As with edge finish, much of what you decide to do with bevel angle will be dictated by the use you have for the blade... and, of course, what the steel will support.

BTW, all of the CRKT knives that I have in S30V are stock 20 degrees per side. The Spyderco I talk about above came to me at close to 20 degrees per side. Folks on KnifeForums swear S30V is good for 15 degrees per side... Almost 22 degrees per side on his Emissary will just make it a bit harder for Mike to get the kind of performance he seems to want. Don't take this as meaning that I think more acute is better in all cases. Fit the bevel to the steel and your use patterns.
You are just less likely to get razor like performance with a large included angle.

Phil
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Last Edit: 1 year 9 months ago by PhilipPasteur.
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Re: S30 V 1 year 9 months ago #8375

  • Mikedoh
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Hi Phil
I appreciate your investigation into S30.
Strokes are all done with only enough pressure to keep the stone "flat" against the edge.
Strokes per side, over 300. Trying to polish things out
Strops were just 20-30 per side.

Now, multiply this by 2+. For stones greater than 1k, since I didn't like my initial results. Stropping was still 20-30.

It puzzles me since I normally have no problem producing an edge, and this one is not as sharp as the other edges I get, nor as shiny.

I'm willing to decrease the angle to 20 or less. Any knife I carry, I just usually figure I should keep a stout edge on it so that it is up to possibly demanding tasks.

Here's something interesting, I emailed Benchmade and asked what angles they used on ther knives, and for a chart if they had one. They replied that all of their knives are sharpened at 15 degrees per side. So, maybe I goofed when I figured the angle using the marker . . . But then, it seems like I should have had an easier time sharpening at 21 per side.

I only did cursory glances at the edge /c magnification, as I expected it would all work out.
Last Edit: 1 year 9 months ago by Mikedoh. Reason: Spelling
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Re: S30 V 1 year 9 months ago #8381

  • mark76
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I guess most appropriapriate remarks have already been made. S30V is much more wear resistant than some other steels, so it simply takes a bit more effort to sharpen. It also doesn’t take an edge like steel like 13C26 or most carbon steels. That said, I can get it wickedly sharp. It easily shaves arm hair. I just cannot get it so sharp that I can comfortably shave my face with it.

Some time ago I asked Spyderco whether their S30V knives could hold a 15 degree angle and their answer was a “yes” without reservations.
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Re: S30 V 1 year 9 months ago #8385

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Mikedoh wrote:
Hi Phil
I appreciate your investigation into S30.
Strokes are all done with only enough pressure to keep the stone "flat" against the edge.
Strokes per side, over 300. Trying to polish things out
Strops were just 20-30 per side.

Now, multiply this by 2+. For stones greater than 1k, since I didn't like my initial results. Stropping was still 20-30.

It puzzles me since I normally have no problem producing an edge, and this one is not as sharp as the other edges I get, nor as shiny.

How much difference do you see? I think it is an accepted idea that S30V doesn't polish as well as som others. BTW, when I went back and searched, I still found lots of folks complaining that they could not get this steel as sharp as the were used to getting other steels. I have found the same thing, but I certainly think the Military is plenty sharp. It just doesn't have that last little bit of keenness that some of my other blades do. So far, from your description of what you did, I really can't make any suggestions on what to change, other than trying a more acute angle.
I'm willing to decrease the angle to 20 or less. Any knife I carry, I just usually figure I should keep a stout edge on it so that it is up to possibly demanding tasks.

What would you do that you would worry about 20 degrees with S30V not holding up to?
Here's something interesting, I emailed Benchmade and asked what angles they used on ther knives, and for a chart if they had one. They replied that all of their knives are sharpened at 15 degrees per side. So, maybe I goofed when I figured the angle using the marker . . . But then, it seems like I should have had an easier time sharpening at 21 per side.

I agree, but it sounds like you have done all of the right things...and then some!

I only did cursory glances at the edge /c magnification, as I expected it would all work out.

It might be worth taking a close look to see if you can determine what is going on. Examining the edge visually can be very instructive, especially when you are having problems.

We also might ask Mark to let us know what he does for his S30V blades, as he seems to have some success with it.

Phil
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Re: S30 V 1 year 9 months ago #8386

  • cbwx34
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Diagnosing these are sometimes hard to pin down, so I'll just throw a few things out..

S30V doesn't polish well for me... always seems to have a misty or hazy look to it.

I think Phil is right, you should lower the angle. 21 almost 22 deg. seems a bit high. I stuck an unsharpened Griptilian in the clamp this a.m..... the edge was between 17-18 deg. Not to say yours couldn't have been a higher angle... but I would double check this.

I've noted that S30V can sometimes develop a wire edge that is hard to detect until you do some actual cutting... it's strong enough to survive light testing, but the edge will quickly dull or "roll" in use. It also won't get as sharp (my guess is it slighty "bends away" from the abrasive as your sharpening or stropping). What I do to get rid of it, is, after sharpening but before stropping, is set a higher angle, 4-5 deg. per side, and lightly, with the finest stone or ceramic I have, make a couple of light edge leading strokes per side to get rid of it. Then return to the original sharpening angle make 1-2 light strokes, then strop or finish the blade however you want. The goal is not to create a microbevel... just clean up the edge.

Keep us posted!
Last Edit: 1 year 9 months ago by cbwx34.
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Re: S30 V 1 year 9 months ago #8388

  • Mikedoh
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Thanks for all your input gentlemen. I'll post more after I've fiddled with it some more, may be a few days, have some unexpected things that require attention.

As to my edge angle and what I might do to harm it with a smaller angle. Heaven only knows, I have made a "few" less than wise choices. The difference in sharpeness between other knives and the s30v steel , is that the others layed flat on the arm and moved with no pressure effortlessly cut hair, while the s30 wants a greater angle and some pressure.
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Re: S30 V 1 year 9 months ago #8399

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Took a look at the edge with a loop. Looks fine. See no burr. Will re sharpen at some lesser angle when I get the chance and post results.

It is sharp, just "not as" other steel given the same course of stones.

Thanks for all replies
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Re: S30 V 1 year 9 months ago #8400

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Maybe just the nature of the beast...
We tend to get very critical after using the WEPS for awhile.
Phil

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Re: S30 V 1 year 9 months ago #8504

  • Geocyclist
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Just finished a Benchmade 940 in S30V. Used diamonds, then Choseras 400-3k. Finished with strops 5m to 0.5. The polish and edge are excellent, very sharp. The polish is not as bright as other steels. But I am impress with how sharp it is. The polish is about mirror, just not super reflective. I will be curious to see how it holds up.

In the end I am pleased, but still wouldn't call S30V my favorite steel.
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